The invention relates to an electromedical apparatus, particularly a stimulation current apparatus comprising a current waveform generator as well as a constant current stage for controlling the output current through a load resistance, preferably the human body of a patient, which functions with a specifiable operating voltage.
Known apparatus of this type, particularly electromedical stimulation apparatus, have a constant current output stage which operates with a relatively high operating voltage (up to several 100 V). This is intended to guarantee that, even in the case of extremely high patient resistances, the currents necessary for therapy or diagnosis, respectively, can be applied with the correspondingly high operating voltage requirement. In the case of a conventional method of treatment, the patient resistances are indeed relatively low (e.g. in the case of application of large-surface electrodes); thus, during application in these normal cases, an operating voltage is needed for the required currents which lies substantially lower than the high operating voltage available. This discrepancy leads to very unpleasant occurrences in those instances when e.g. the patient resistance is suddenly varied; this particularly applies to the instance in which the current supply electrodes have become disengaged at the application location and have finally completely dropped off. At the moment of detachment, namely, the area of current passage becomes rapidly reduced such that, in conjunction with the characteristic of a constant current source, the current density on the skin takes on very high values at the application location. This leads to a very unpleasant, painful irritation of the patient treated. In many instances, also, direct burns of the skin are brought about as a consequence. If the supply electrodes have finally completely dropped off, the full, dangerously high operating voltage is connected between the electrodes as long as the apparatus is still in operation and continues to function with the previously set intensity.